Circuit interrupter



Feb. 5, 1952 R. E. FRINK CIRCUIT INTERRUPTER Filed Feb. 7, 1950 2 SHEETS-SHEET l INVENTOR 2 SHEETS-SHEET 2 n Russell E. Frink.

Fig.

Feb. 5, 1952 R. E. FRINK CIRCUIT INTERRUPTER Filed Feb. '7, 195o F ig.4.

Patented Feb. 5, 1952 UNITED STATES OFFICE CIRCUIT Russell .E-.f Frink,r-Pittsburgh, Pa., assignerto.V Westinghouse :Electric Corporation, East' Pittsbur-gh, Pa., a corporation of Pennsylvania Applicationv February 7, 1950",--Se1'=iall No."142,875

2 Claims. (Cl. 20o-147) This invention/relatesto circuit interrupters in general, and more vparticularlyto arc extinguishing structures therefor.

A general object of" my invention is'to provide anirnpr'oved. arc extinguishing structure of the spaced plate typein whichthemagnetic iield is intensiedtoathereby effect more rapid movement and faster 4extinction of they established' arc.

Another object ,isi to L provide an improved spaced plate'typefof arc extinguishing :structure of fthe: type 'having aipluralityxof spaced plates with offsetslots'extendingtherein, iny which the oiset distance between the closed ends of divergeing offset slotsf may :beincreasedr byA a novel intensication of the magnetic field.

A iurther object is .topprovidepairsof'cooperating oifs'et slotted platesv in which the offset distance of one plate of` a .pairof'plates isgreater than the offset distance ofrfther other of` lthepair of plates. Preferably thepairslof plates Yare so disposed so thatl theoffsetfslots are disposed iirst to one-sideof the centerline ofethearcfchutesand then Vto vthe yother side of. the :centerlineof` thearc chute:

A further object is to' provide an improved spaced plate type ofarci extinguishing structure,

Y Figure 1 is aside elevational view,- partially in vertical section,..of a, circuit interruptor embodying my invention and shown in the `closedcircuit position.;

Flig'sZv lssa .verticalsectional view ltaken along the lline II--II of Fig.j1.lookingfin thedirection of n the, arrows ;1

Fig: 3 is an enlargedplan view in sectiony taken along the linefLIII--III` of Figi. 2, .lookingin the direction of the arrows; and f Figs. 4-6 are side views .of Aplatedetails usedin The..:contact .structure 2 comprises a terminal stud Iil surrounded by insulating bushings 1,'Ia. and supporting a stationary main contact plate 8. The contactA plate 8 forms a main. stationary contact 9,-andin addition supportsy a relatively stationary,v secondary. contact` I0 and' a relatively stationaryk ,arcing contact I I;

The-:other terminal studior the interrupter I is notshown, butisupports a` second stationary main contact` I2,and in addition ypivotally. supportsai'main moving contact arm. I 3 which,v wbeing pivotall-y mountedfis adaptable to swing, ,during the'zopening.operation, in a clockwise direction aboutr its pivot point to. rst 4cause separation between a conducting'bridge I4` and the stationarymainy contactsY 9,` I2. Subsequentlyv the continued 'clockwise openingl rotative motion of the moving contact arm I3 causesy separation betweenthey secondary arci-ng contacts III,` I5, ywhich separationfis subsequently followed by separation-between thearcing contacts .I I, I6. Suitablebiasing springs andfstops are provided. to give thel desired` sequence in the contact separation.

Becausezof the loopcircuit formed, bythe two terminalrzstuds and the -main contact arm I3, andA because ot venting out ofthe arc `chute at the point-5,1 the arc I'Ifwhich isinitiallyestablished between-the arcing contacts II, I6, bows upwardly to' contact the are horny I8. and thereby insert.A into ,series` circuit the-,blowout coil rI9. oi theblowout assembly'. Theposition of the arc at-thispoint-is designatedcby thereference charactor-20. The energization of theblowout coll IQ..y sets up'xaftransverse magnetic eld between thezpole -plates 2I-to further move therarc 20 upwardly intoV thearc chute 4. Subsequently theright-hand end .off the arc 240 transfersto the-:right-hand-arc'horn 272,and at Vthisctixne the i electrical circuitfthrough the` interrupter includes lterminal stud 6,fcontact plate 8,connector 23, blowout .coil I9, arc horn I8, the arc 24 the right-hand arc `hcrn22, .flexible ,conductor 25, and: through the main.r contact arm I3 to the lower termi-nal' studfofy theinterrupter I, not shownVv y Referring more particularly to FigsQ-S, which collectively illustrate .the construction of my improved arc` ch-ute,. it will be `apparent thatA the are chute 4- comprises pairs of'lrefr'actory, nonevolving,y insulatingv` plates 26,- ZBvwhch have oiset-closedslots .21, 21a, as more clearly shown in- Figs.- 4-andv`5. twill be observedfthat the distance D, lwhich' is .the distance between the lclosed/'end ofv the offset slot 'Iaand the rigl'itf hand lside .of. the-plate 26o, as rviewed 'in 5,

3 is less than the distance D1, which is the distance between the closed end of the offset slot 21 of the plate 26 and the right-hand side of said plate 28, as shown in Fig. 4.

The arc chute 4 is built up of pairs of the plates, 2B, 26a, with the offset slots first to one side of the centerline 28 of the arc chute 4, and then to the other side of the centerline 28 of the arc chute 4, as shown more clearly in Fig. 3.

Disposed between the two plates 26, 26a ofV each pair of plates is a magnetic filler plate 29, more clearly shown in Fig. 6. As indicated in Figs. 3 and 6 the magnetic ller plate 29 appears to be a single plate of magnetic material. However, in practice, it would be desirable to have the magnetic ller plate 29 composed of laminations cemented together to reduce losses.

Y l gas in considerable quantities.

The arc chute 4, comprises a sub-assembly 30 including the pairs of plates 26, 26a, together with the magnetic filler plates 29 cemented together with asbestos rope 3l as a spacing means. In other words, the asbestos rope 3l is coated with cement and placed between the several plates, as shown in Fig. 3, the resulting sub-assembly 39 being placed under pressure and baked. Following baking, the sub-assembly 3u is a unitary structure which may be bodily placed within the arc chute housing or jacket 33, and maintained in position by the use of insulating holding strips 34 which are bolted by bolts 35 to the insides of the upper side of the housing 33. The holding strips 34 prevent the gas pressure created during the interruption process from blowing the sub-assembly 30 upwardly out of the housing 33.

The arc 24 is forced upwardly by the transverse magnetic field, extending between the pole plates 2i, within the offset slots 21, 21a to the position shown in Fig. 3. It will be observed that the magnetic plates 29 cause the flux lines of the magnetic eld to become distorted as indicated by the reference character 36, as viewed in Fig. 3, so that throughout the length of the arc 24 it is acted upon by the magnetic field.

It is, of course, well known by those skilled in the art that the force which causes upward movement of the arc 24 is proportional to the current passing through the arc 24 and to the component of the magnetic field which is at right angles to the arc. Since only the component of the arc at right angles to the magnetic eld is appreciably affected by the magnetic eld, this limits the amount of offset between the diverging ends of the slots. Consequently without the use of the magnetic plates 29, the magnetic eld would be substantially parallel to portions of the arc 24 extending between the offset slots 21, 21a, and hence would have no driving effect upon these portions of the arc 24. The result is that there is a limiting ratio of offset distance to plate thickness plus plate spacing.

In other words, the parallel portions of the arc would not rise as rapidly as the curved portions of the arc curving around the closed ends of the slots, and the curved portions of the arc would hence restrike back to the parallel portions.

However, by distorting the magnetic field by the use of the magnetic filler plates 29, the magnetic field makes a substantial angle to the direction of the arc even though the arc is extensively folded upon itself by the use of highly offset slotted plates. Furthermore, there is a benecial effect in arc interruption derived from the magnetically induced gas blast present when the direction of arc and the field are other than parallel, which is not present over the length of to the electrons an upward velocity.

turn bombard gas particles and produce an ac- 4 arc parallel to the field. This effect is described in AIEE Technical Paper 46-55 by R. C. Dickinson and R. E. Frink, pages 220-223, volume Transactions for the AIEE 1946 as follows: it [magnetic de-ionizationl consists of moving the arc toward the closed tops of slots in insulating arc resisting plates. At this position, the presence of a strong magnetic field imparts They in tual blast of gas perpendicular to the arc, which action requires the arc continually to ionize fresh When current zero is reached, this action continues in a sufficient degree effectively to de-ionize the plurality of short lengths of arc near the edges of the slots.

To impart this upward velocity to the electrons the magnetic field must have a component in quadrature to the direction of current flow.

From the foregoing disclosure it will be apparent that I have provided an improved arc chute in which the magnetic flux is so changed or distorted by the magnetic plates 29 that the arc 24 is always at approximately right angles to the eld. The purpose in making the plates 26, 26a with diiferent offsets 21, 21a is to change the direction of the arc 24 asmany times as possible which tends to free it of heavier particles carried along in the arc stream. It will be observed that the foregoing structure accomplishes three objectives:

(l) The magnetic field is working on the arc throughout its length so that the limiting ratio of offset to plate thickness plus spacing may be removed, and it is possible to put as much offset in the plates as space will permit;

(2) By keeping the magnetic field at right angles to the arc 24 throughout its length, better deionizing action is obtained; and

(3) The presence of the iron decreases the effective length of the air gap between the pole pieces 2l and makes higher field strengths possible.

It will be apparent from the foregoing descrip tion of a preferred embodiment of my invention that I have provided an improved arc chute of the spaced plate type in which by the use of magnetic filler plates 29, the magnetic field has been distorted to more effectively propel the arc upwardly within the spaced plates so that an increase in offset distance may be employed. Furthermore deionization along the length of the arc has been effectively increased by the additional magnetic driving effect and by the loss of the heavier particles in the arc stream as the latter changes its direction.

Although I have shown and described a specinc structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the 'art without departing from the spirit and scope of the appended claims.

I claim as my invention: l. A circuit interrupter including means for 'establishing an arc, an arc chute for extinguishing the arc including a plurality of spaced pairs of insulating plates having closed offset slots provided therein, the closed ends of the offset slots of each pair being disposed to the same side of rthe centerline of the arc chute, the closed ends of the offset slots of one pair of insulating plates being disposed to the opposite side of the center line than that of the immediately adjacent pair of insulating plates, thereby to form a substantially zigzag arc passage transversely of the direction of motion of the arc through the arc chute, blowout means including a pair of pole plates disposed on opposite sides of the center line of the arc chute, and a plate of magnetic material disposed between each pair of insulating plates sandwiched therebetween and having one side edge thereof extending immediately adjacent the pair of slots provided in such pair of insulating plates, the opposite side of each lsuch magnetic plate extending adjacent to the pole plate on the opposite side of the centerline of the arc chute than that of the closed ends of the oiT- set slots of such pair of insulating plates.

2. A circuit interrupter including means for establishing an arc, an arc chute for extinguishing the arc including a plurality of spaced pairs of insulating plates having closed offset slots provided therein, the closed ends of the offset slots 2 of each pair being disposed to the same side of lthe centerline of the are chute, the closed ends of the offset rslots of one pair of insulating plates being disposed to the opposite side of the centerline than that of the immediately adjacent pair of insulating plates, thereby to form a substantially zigzag arc passage transversely of the direction of motion of the arc through the arc chute, blowout means including a pair of pole plates disposed on opposite sides of the centerline of the arc chute, a plate of magnetic material disposed between each pair of insulating plates sandwiched therebetween and having one side edge thereof extending immediately adjacent the pair of slots provided in such pair of insulating plates, the opposite side of each such magnetic plate extending adjacent to the pole plate on the opposite side of the centerline of the arc chute than that of the closed ends of the offset slots of such pair of insulating plates, the amount of offset in the slot of one insulating plate of one pair of insulating plates being different than the amount of offset in the other insulating plate of such pair of insulating plates to thereby cause the arc to change directions as much as possible to facilitate its extinction.

RUSSELL E. FRINK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,840,292 Slepian Jan. 5, 1932 2,293,487 Bartlett Aug. 18, 1942 2,306,204 Boehne Dec. 22, 1942 

